And "Show Hogs"....6 people that trade off squat duties for 15 minutes apiece. One person hoards 6 seats for 15 minutes and then passes the baton to another....and then to another.
Decent passengers lose out while a group gets all the seats with little effort on the part of an individual.

How about "Rude old curmudgeon"? That is me when meeting a "Show Hog". DW and I simply sit down in two of their seats (hopefully the middle two) and smile and say, "There is a policy on this ship of not reserving seats, you know."